Sensitivity of communities' trait-based indices to species selection

Trait-based indicators offer insights into environmental impacts on communities but are often limited by the availability of species traits data, relying on subsets that may omit less studied taxa, leading to bias. To address this, we tested the species selection's influence on trait-based indices using filters based on occurrence, species' distributions, and abundance. Using data from two bottom-trawl surveys, we compiled 15 traits for the 246 most common demersal species in two temperate ecosystems in the North-East Atlantic and Mediterranean Sea. Our analyses revealed that trait data is strongly biased toward abundant and large species, particularly those of commercial importance or conservation concern. While species selection had minimal impact on community traits, excluding invertebrates strongly affected the results, highlighting their key role in community dynamics.

We thank all the dedicated people of the Instituto Español de Oceanografía (IEO, CSIC, Spain), who have worked on the DEMERSALES and MEDITS surveys research vessels. These surveys are funded by the IEO and the European Union (EU) through the European Maritime and Fisheries Fund (EMFF) within the National Program for data collection, management, and use in the fisheries sector, providing scientific advice for the Common Fisheries Policy. We are grateful to Luis Gil de Sola for his assistance with data curation. This work received support from the VADAPES project, funded by the Biodiversity Foundation of the Spanish Ministry for the Ecological Transition and the Demographic Challenge, and the COCOCHA project (Grant PID2019-110282RA-I00 funded by MCIN/AEI/ 10.13039/501100011033). L.L-L. was supported by a contract financed through the “Juan de la Cierva Incorporación 2020” fellowship [IJC2020-043235-I] funded by MCIN/AEI/ 10.13039/501100011033 and the European Union”NextGeneration EU/PRTR”.

Peer reviewed